Circuit pattern inspection device and circuit pattern inspection method

ABSTRACT

Disclosed is a circuit pattern inspection apparatus for inspecting a plurality of target patterns  15  arrange in lines at least at first and second opposite ends thereof. The inspection apparatus comprises a supply electrode  35  for supplying an inspection signal and a sensor electrode  25  for detecting a detection signal. Each of the supply and sensor electrodes  35, 25  are adapted to be moved across each of the target patterns with a given gap relative to each of the target patterns  15  in such a manner as to allow the inspection signal supplied from the supply electrode  35  to each of the target patterns  15  through a capacitive coupling, to be detected by the sensor electrode capacitively coupled with each of the target patterns  15 , so that the presence of disconnection in the target pattern is determined when the detection signal has a value less than a given lower limit, and the presence of short circuit in the target pattern is determined when the detection signal has a value greater than a given upper limit. According to the inspection apparatus of the present invention, the presence of defect in a circuit board can be inspected reliably and readily.

TECHNICAL FIELD

The present invention relates to a circuit pattern inspection apparatusand method adapted to inspect the presence of defect in a plurality ofconductive patterns formed on a circuit board.

BACKGROUND ART

A manufacturing process of a circuit board with a plurality ofconductive patterns formed thereon unexceptionally include an operationfor inspecting whether a disconnection and a short circuit exist in eachof and between the conductive patterns.

Heretofore, as a technique for inspecting a plurality of conductivepatterns, there has been known a contact (pin contact) method forinspecting a quality parameter, such as conduction, of the conductivepatterns, which comprises binging a plurality of pins into contact,respectively, with first and second opposite ends of the conductivepatterns, supplying an electrical signal from the pins in contact withthe first ends to the conductive patterns, and receiving the electricalsignal from the pins in contact with the second ends, as disclosed, forexample, in the following Patent Publication 1. In the pin contactmethod, the electrical signal is supplied by putting a plurality ofmetal probes serving as the pins, respectively, on all terminals of theconductive patterns, and applying a current from the probes to theconductive patterns.

The pin contact method based on the pin probes in direct contact withthe terminals provides an advantage on a high S/N ratio.

Late years, in connection with densification of conductive patterns, thepitch of connecting wirings has become narrower, partly, to less than 50μm. Accordingly, a probe card is required to have a number ofnarrower-pitch probes, which drives up a manufacturing cost thereof.

Moreover, the probe card has to be newly prepared for each circuit boarddifferent in wiring patterns or on an inspection target-by-inspectiontarget basis. This leads to increase in inspection cost, resulting inhindrance to cost reduction of electronic components.

Further, the probe card with a microstructure is fragile, and therebyhas to be used with full attention to avoiding damages thereof duringactual inspection.

In that context, a contact-non-contact combinational method has alsobeen proposed that comprises applying an inspection signal including anAC component from a plurality of pin probes in direct contact,respectively, with first ends of a plurality of conductive patterns tobe inspected (a pattern to be inspected will hereinafter be referred tooccasionally as “target pattern”), and detecting the inspection signalfrom a probe positioned in non-contact manner with respect to or inspaced-apart relation to second ends of the conductive patterns by agiven distance, through a capacitive coupling therebetween, asdisclosed, for example, in the following Patent Publication 2.

In the contact-non-contact combinational method, the probe to bepositioned relative to the second ends of the conductive patterns has noneed to be brought into direct contact with the conductive patterns.Thus, the non-contact probe may be roughly positioned without the needfor assuring a high degree of accuracy as in the pin probes. Inaddition, a single non-contact probe can be shared with the plurality ofconductive patterns to reduce the number of probes. Thus, this methodcan be valid even if the second ends of the conductive patterns arefinely spaced.

-   -   Patent Publication 1: Japanese Patent Laid-Open Publication No.        62-269075    -   Patent Publication 2: Japanese Patent Laid-Open Publication No.        11-072524

In the contact-non-contact combinational method, respective probes to bepositioned relative to the first and second ends of the conductivepatterns, and a processing of the detection signal from the non-contactprobe, are specifically designed depending on the intervals betweenconductive patterns. Thus, the probes and the processing can be used foronly one type of circuit board with conductive patterns having aspecific configuration or arrangement. Moreover, an associated jig hasto be prepared for each circuit board different in conductive patterns.

Further, while the pin probes have to be brought into direct contact,respectively, with the first ends of the conductive patterns, as aprerequisite for the contact-non-contact combinational method,accelerated densification in the first ends makes it difficult to ensurethe contact between the pin probes and the first ends. Furthermore, itis intrinsically difficult to avoid the risk of damages in conductivepatterns or target patterns, due to the contact with the pin probes.

DISCLOSURE OF INVENTION

In view of the above conventional problems, it is therefore an object ofthe present invention to provide an apparatus and method capable ofinspecting fine wiring patterns in a simplified structure, andresponding to change in wiring patterns.

In order to achieve this object, according to a first aspect of thepresent invention, there is provided a circuit pattern inspectionapparatus for inspecting a plurality of target patterns having first andsecond opposite ends included in an inspection region thereof andarrange in lines, which is adapted to supply an AC inspection signalfrom the first end side of the inspection region of the target patterns,and detect a signal from the second end side of the inspection region.The circuit pattern inspection apparatus comprises supply meansincluding a supply electrode for supplying the inspection signal fromthe first end side of the inspection region of the target patterns,detection means including a sensor electrode for detecting a signal fromeach of the target patterns, and moving means for moving the supply andsensor electrodes, respectively, across the first and second endsincluded in the inspection region and arrange in lines, with a given gaprelative to each of the target patterns.

In the circuit pattern inspection apparatus set forth in the firstaspect of the present invention, each of the target patterns may be aconductive pattern formed on a circuit board to have a bar-like shapewith a given width.

In the circuit pattern inspection apparatus set forth in the firstaspect of the present invention, the sensor electrode may have a widthequal to or greater than a width of two lines of the target patterns.

In the circuit pattern inspection apparatus set forth in the firstaspect of the present invention, the sensor electrode may include afirst sensor electrode adapted to be disposed at a position opposed tothe second end of one of the adjacent target patterns which has thefirst end supplied with the inspection signal from the supply electrode,and a second sensor electrode adapted to be disposed at a positionopposed to the second end of a remaining one of the adjacent targetpatterns.

The first sensor electrode may have a width equal to or less than eachwidth of the target patterns. The second sensor electrode may have awidth equal to or less than each width of the target patterns.

In the circuit pattern inspection apparatus set forth in the firstaspect of the present invention, the moving means may be adapted to movethe supply and sensor electrodes, respectively, across the first andsecond ends included in the inspection region and arrange in lines,under the condition that each surface of the supply and sensorelectrodes is capacitively coupled with each of the target patterns.

The circuit pattern inspection apparatus set forth in the first aspectof the present invention may further include determination meansoperable, when a detection result of the detection means based on adetection signal from one of the target patters is in a given acceptablerange, to determine that the target pattern is normal, and, when adetection result of the detection means based on a detection signal fromone of the target patters is out of the given acceptable range, todetermine that the target pattern is defective.

In this case, the circuit pattern inspection apparatus may includesecond moving means for moving the supply and sensor electrodes torespective positions opposed to the first and second ends of thedefective target pattern determined by the determination means, andmoving either one of the supply and sensor electrodes along thedefective target pattern toward the other electrode, and positiondetection means for detecting a position where a detection signal fromthe defective target pattern has a change, in accordance with adetection result of the detection means.

Further, the circuit pattern inspection apparatus may include contactingmeans for bringing either one of the supply and sensor electrodes intocontact with the defective target pattern.

At least one of the supply and sensor electrodes which is to be moved bythe second moving means may include an image pickup means.

The above circuit pattern inspection apparatus may include a gap controlmeans for positioning at least one of the supply and sensor electrodeswhich is to be moved by the second movement means, in such a manner asto allow a gap between the at least one electrode and the defectivetarget pattern to be maintained at an approximately constant value.

The circuit pattern inspection apparatus set forth in the first aspectof the present invention may include a gap control means for positioningat least one of the supply and sensor electrodes to be moved by themovement means, in such a manner as to allow a gap between the at leastone electrode and each of the target patterns to be maintained at aconstant value.

The gap control means may include a displacement measurement devicedisposed at a position adjacent to the sensor or supply electrode andadapted to be moved together with the sensor or supply electrode, thegap control means being operable to position the sensor or supplyelectrode in a direction orthogonal to the inspection region inaccordance with a detection result of the displacement measurementdevice, in such a manner as to allow a gap between the sensor or supplyelectrode and the inspection region to be maintained at an approximatelyconstant value

Further, the gap control means may be operable to position the sensor orsupply electrode in a direction orthogonal to the inspection region, onthe basis of a gap between the sensor or supply electrode and theinspection region which is defined by an average displacement of adetection result of the displacement measurement device obtained from aplurality of pitches of the target patterns.

According to a second aspect of the present invention, there is provideda circuit pattern inspection method for use in a circuit patterninspection apparatus which comprises supply means including a supplyelectrode for supplying an inspection signal to each of a plurality oftarget patterns having first and second opposite ends included in aninspection region thereof and arrange in lines, from the first end sideof the inspection region, and detection means including a sensorelectrode for detecting a signal from each of the target patterns. Thecircuit pattern inspection method comprises moving the supply and sensorelectrodes relative to the target patterns, respectively, across thefirst and second ends included in the inspection region and arrange inlines, under the condition that each surface of the supply and sensorelectrodes is spaced apart from each surface of the target patterns,supplying an AC inspection signal from the first end side of theinspection region of the target patterns, and detecting a signal fromeach of the target patterns to inspect the target patterns.

In the circuit pattern inspection method set forth in the second aspectof the present invention, each of the target patterns is a conductivepattern formed on a circuit board to have a bar-like shape with a givenwidth.

This circuit pattern inspection method may include allowing the sensorelectrode to have a width equal to or greater than a width of two linesof the target patterns, and detecting a signal from one of the adjacenttarget patterns a remaining one of which is supplied with the inspectionsignal, so as to allow the presence of short circuit between theadjacent target patterns to be determined.

The circuit pattern inspection method set forth in the second aspect ofthe present invention may include detecting a signal from one of theadjacent target patterns which is supplied with the inspection signal,through a first sensor electrode included in the sensor electrode so asto allow the presence of disconnection in the target pattern to bedetermined, and detecting a signal from a remaining one of the adjacenttarget patterns through a second sensor electrode included in the sensorelectrode so as to allow the presence of short circuit between theadjacent target patterns to be determined.

The circuit pattern inspection method set forth in the second aspect ofthe present invention may include determining a general position of adisconnected region in the target pattern in accordance with a positionof the sensor electrode where the detection means has no detectionsignal.

The circuit pattern inspection method set forth in the second aspect ofthe present invention may include evaluating whether a detection resultof the detection means based on a detection signal from one of thetarget patters is in a given acceptable range, wherein when thedetection result is in a given acceptable range, determining that thetarget pattern is normal, and, when the detection result is out of thegiven acceptable range, determining that the target pattern isdefective.

This circuit pattern inspection method may include: specifying aposition of the defective target pattern determined by the determinationmeans and storing information about the position; moving the supply andsensor electrodes to respective positions opposed to the first andsecond ends of the defective target pattern in accordance with thestored information; moving either one of the supply and sensorelectrodes along the defective target pattern toward the otherelectrode; and detecting a position where a detection signal from thedefective target pattern has a change, in accordance with a detectionresult of the detection means, and defining the position as a defectiveposition.

Further, the circuit pattern inspection method may include bringingeither one of the supply and sensor electrodes into contact with thedefective target pattern.

The circuit pattern inspection method may include providing image pickupmeans in either one of the supply and sensor electrodes, and moving theimage pickup means together with the at least one electrode along thedefective target pattern toward the other electrode.

The circuit pattern inspection method set forth in the second aspect ofthe present invention may include providing a displacement measurementdevice disposed at a position adjacent to the sensor or supply electrodeand adapted to be moved together with the sensor or supply electrode,and positioning the sensor or supply electrode in a direction orthogonalto the inspection region in accordance with a detection result of thedisplacement measurement device, in such a manner as to allow a gapbetween the sensor or supply electrode and the inspection region to bemaintained at an approximately constant value, so as to provide a stabledetection result of the detection means.

This circuit pattern inspection method may include positioning thesensor or supply electrode on the basis of a gap between the sensor orsupply electrode and the inspection region which is defined by anaverage displacement of a detection result of the displacementmeasurement device obtained from a plurality of pitches of the targetpatterns.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram of an inspection principle in a circuitpattern inspection apparatus according to a first embodiment of thepresent invention.

FIG. 2 is a flowchart of an inspection control process in the circuitpattern inspection apparatus according to the first embodiment.

FIG. 3 is a waveform chart showing one example of a detection signalobtained by the circuit pattern inspection apparatus according to thefirst embodiment when three target patterns have a disconnected (open)region.

FIG. 4 is a waveform chart showing one example of a detection signalobtained by the circuit pattern inspection apparatus according to thefirst embodiment when one target pattern has a short-circuited (short)region.

FIG. 5 is a block diagram showing a circuit pattern inspection apparatusaccording to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a circuit pattern inspection apparatusaccording to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a process of moving electrodes, inthe circuit pattern inspection apparatus according to the thirdembodiment.

FIG. 8 is a flowchart of a process of specifying a defective-regionposition, in the circuit pattern inspection apparatus according to thethird embodiment.

FIG. 9 is a waveform chart showing one example of a detection signalobtained from a defective target pattern through a sensor electrode inthe circuit pattern inspection apparatus according to the thirdembodiment.

FIG. 10 is a waveform chart showing one example of a detection signalobtained from the sensor electrode through a defective target pattern.

FIG. 11 is a block diagram showing a circuit pattern inspectionapparatus according to a fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the drawings, the present invention will now bedescribed in detail in connection with a specific embodiment thereof.

While the following description will be made on the assumption that acircuit pattern inspection apparatus according to the embodiment isdesigned to inspect the presence of defect in a dot-matrix patternformed on a circuit board before being incorporated in a dot-matrixliquid-crystal display panel, the present invention is not limited tothe following embodiment, but may be applied to inspection for anycircuit board in which at least a plurality of target patterns haveopposite end portions arranged in rows or lines.

First Embodiment

FIG. 1 is an explanatory diagram of an inspection principle in a circuitpattern inspection apparatus according to a first embodiment of thepresent invention.

In FIG. 1, the reference numeral 10 indicates a circuit board formedwith a plurality of conductive patterns 15 to be inspected by theinspection apparatus according to the first embodiment. In thisembodiment, the circuit board 10 is a glass circuit board for use in adot-matrix liquid-crystal display panel. The conductive patterns 15 arearranged in lines at even intervals on a surface of the glass circuitboard 10. Each of the conductive patterns 15 illustrated in FIG. 1 hasapproximately the same width. While the conductive patterns 15 arearranged at even intervals, the inspection apparatus according to thefirst embodiment can perform an adequate inspection even if theconductive patterns are arranged at uneven intervals.

The reference numeral 20 indicates a sensor section; 30 indicates aninspection signal supply section; 50 indicates an analog signalprocessor for processing a detection signal from the sensor section 20and sending the processed signal to a control unit 60 for generallygoverning the control of the inspection apparatus; and 70 indicates arobot controller for controlling a scalar robot 80 which is operable tomove and hold the circuit board 10 to/in an inspection zone, and thenscanningly move a sensor electrode 25 of the sensor section 20 and asupply electrode 35 of the inspection signal supply section 30 in such amanner that they sequentially get across all connection terminals of theconductive patterns or target patterns, under the control of the robotcontroller 70.

In this embodiment, the scalar robot 80 has a three-dimensionalpositioning function for moving and holding the circuit board 10 to/in agiven inspection zone, and moving the sensor section 20 and theinspection signal supply section 30 above the target patterns with agiven distance relative to the surface of the circuit board 10.

While the above inspection apparatus is designed such that the scalarrobot 80 is controlled to move the sensor section 20 and the inspectionsignal supply section 30 above the target patterns with a given distancerelative to the surface of the circuit board 10, the present inventionis not limited to such a control. Specifically, the sensor section 20and the inspection signal supply section 30 may be fixed, and the scalarrobot 80 may be controlled to move the circuit board 10 with a givendistance relative to the respective electrodes 25, 35 of the sensorsection 20 and the inspection signal supply section 30, so as to obtainthe same effect.

In an actual inspection, if the target patterns are arranged at unevenintervals or their opposite ends or terminals are different in patternpitch, the sensor electrode 25 and the supply electrode 35 have to besynchronizingly moved in such a manner that, when the supply electrode35 is located above one end of a specific one of the target patterns tosupply an inspection signal thereto, at least a portion of the sensorelectrode 25 is located above the other end of the specific targetpattern (one end of each target pattern on the side of the supplyelectrode 35 and the other end of the target pattern on the side of thesensor electrode 25 will hereinafter be referred to respectively as“first end (or first terminal)” and “second end (or second terminal)”).Thus, even if the target patterns are arranged at uneven intervals ortheir first and second opposite ends are different in pattern pitch, anadequate inspection can be performed by simply controlling the scalarrobot to adjust respective movement speeds of the sensor and supplyelectrodes.

In this embodiment, the sensor electrode 25 is provided on at least aportion of a top surface of the sensor section 20, and the supplyelectrode 35 is provided on at least a portion of a top surface of theinspection signal supply section 30. Each of the sensor electrode 25 andthe supply electrode 35 are made of metal, such as copper (Cu) or gold(Au). Each of the electrodes 25, 35 may be coated with a protectiveinsulating material. While each of the electrodes 25, 35 may be made ofa material other than metal, such as semiconducting material, the metalelectrode makes it possible to obtain a larger electrostatic capacityrelative to the conductive patterns.

The inspection signal supply section 30 is moved across the firstterminals of the target patterns by the scalar robot 80, so as tosequentially supply the inspection signal to the target patterns througha capacitive coupling. Preferably, the outermost surface of the supplyelectrode 35 has a width equal to or less than one pitch of the targetpatterns (or a width equal to or less than the sum of the width of onetarget pattern and the interval or distance between the adjacent targetpatterns).

If the width of the supply electrode 35 is greater than the pitch of thetarget patterns, the sensor electrode 25 of the sensor section 20 islikely to detect the inspection signal from three or more of the targetpatterns.

However, it is not essential for the supply electrode 35 to have a widthequal to or less than one pitch of the target patterns. Specifically,the inspection apparatus may be designed to have a sensor sectioncapable of figuring out each state of two or more of the target patternsand the target patterns adjacent thereto, and perform an inspectionaccording to an inspection process described in detail later.

The sensor section 20 is moved across the second terminals of the targetpatterns 10 by the scalar robot 80, so as to sequentially detect theinspection signal from the inspection signal supply section 30 through acapacitive coupling. Preferably, the outermost surface of the sensorelectrode 25 has a width greater than the width of the supply electrode35 by at least one pitch of the target patterns.

A detection signal from the sensor section 20 is sent to the analogsignal processor 50, and subjected to an analog signal processingtherein. The processed analog signal is sent from the analog signalprocessor 50 to the control unit 60 to determine the presence of defectin the target patterns 10 associated with the inspection signal supplysection 30. The control unit 60 is also operable to controllably supplythe inspection signal to the inspection signal supply section 30.

The analog signal processor 50 comprises an amplifier 51 for amplifyingthe detection signal from the sensor section 20, a band-pass filter 52for eliminating noise components of the amplified detection signal fromthe amplifier 51 and outputting the filtered detection signal, arectification circuit 53 for full-wave-rectifying the filtered detectionsignal from the band-pass filter 52, and a smoothing circuit 54 forsmoothing the full-wave-rectified detection signal from therectification circuit 53. In the analog signal processor 50, therectification circuit 53 and the smoothing circuit 54 may be omitted.

The control unit 60 for generally governing the control of theinspection apparatus comprises a central processor (CPU) 61, a ROM 62for storing a control program to be executed by the CPU 61 and others, aRAM 63 for temporarily storing information about progress of processingin the CPU 61, the detection signal and others, an A/D converter 64 forconverting the analog signal from the analog signal processor 50 to acorresponding digital signal, a signal supply section 65 for supplyingan inspection signal to the inspection signal supply section 30, and adisplay section 66 for displaying an inspection result, an operationalinstruction/guidance and others.

The signal supply section 65 generates an inspection signal having, forexample, of an AC sine wave of 200 kHz and 200 V, and supplies theinspection signal to the inspection signal supply section 30. In thiscase, the band-pass filter 52 is set to allow the inspection signalhaving a given frequency, such as 200 kHz, to pass therethrough. It isto be understood that the inspection signal is not limited to the sinewave, but may be any other suitable AC signal having, for example, arectangular or pulse wave.

With reference to the flowchart illustrated in FIG. 2, a control processof inspecting the conductive patterns in the above circuit patterninspection apparatus according to the first embodiment will be describedbelow.

In the inspection process using the inspection apparatus according tothe first embodiment, the glass circuit board 10 formed with theconductive patterns or target patterns is transferred along a transferpath (not shown) to a station for the circuit pattern inspectionapparatus (work station). Then, in Step S1, the circuit board 10(hereinafter referred to as “target board”) is set up in the inspectionapparatus. The automatically transferred target board may beautomatically set up in the inspection apparatus using a transfer robot(not shown) or may be manually set up in the inspection apparatus by anoperator. Upon completion of the setting of the target board in theinspection apparatus, the control unit 60 activates the robot controller70 to control the scalar robot 80 so as to move and hold the targetboard to/in an inspection zone.

Subsequently, in Step S3, the supply electrode 35 of the inspectionsignal supply section 30 is moved to an initial position on the side ofthe first ends of the target patterns 15 of the target board 10 (aposition spaced apart upward from the first end of the endmost targetpattern by a given distance), and the sensor electrode 25 of the sensorsection 20 is moved to an initial position on the side of the secondends of the target patterns (a position spaced apart upward from thesecond end of the endmost target pattern by a given distance).

In this embodiment, the distance or gap between each of the targetpatterns and each of the electrodes 25, 35 is maintained in a givenrange, for example, of 100 to 200 μm. The gap is determined by the sizeof the target pattern, and thereby the value of the gap is not limitedto the above range. Specifically, the gap may be set at a larger valueas the size of the target pattern becomes larger, and should be set at asmaller value as the size of the target pattern becomes smaller.

If the target pattern has a significantly small size or the gap has tobe reduced, each surface of the electrodes may be coated with aninsulating material to prevent a direct contact between the targetpattern and the electrode. In this case, the insulation material may beformed to have a thickness approximately equal to the gap or to allowthe sensor section 20 and the inspection signal supply section 30 to bebrought into direct contact with the target board through the insulatingmaterial. This makes it possible to maintain the distance between eachof the target patterns and each of the electrodes at a constant valuereadily and accurately during inspection. Thus, even if the target boardhas significantly fine conductive patterns, an accurate inspectionresult can be readily obtained in a simplified structure.

Subsequently, in Step S5, the CPU 61 instructs the signal supply section65 to start to supply the inspection signal to the supply electrode 35of the inspection signal supply section.

Then, the process advances to Step S7 to start a control forsynchronizingly moving the electrodes 25, 35 of the sensor section 20and the inspection signal supply section 30 across the target patterns,and maintaining the distance between each of the target patterns andeach of the electrodes 25, 35 at a constant value. Under this control,the sensor electrode 25 will sequentially detect a signal potential fromeach of the target patterns supplied with the inspection signal from thesupply electrode 35 through the capacitive coupling therebetween.

Specifically, the sensor electrode 25 is controllably moved in such amanner that, when the supply electrode 35 is located at a positionopposed to a specific one of the target patterns to supply theinspection signal thereto, at least a portion of the sensor electrode 25is located opposed to the second end of the specific target patternsupplied with the inspection signal. Further, the sensor electrode 25 onthe side of the second ends is controllably moved by one pitch of thetarget patterns as the supply electrode 35 on the side of the first endsis moved by one pitch of the target patterns.

Simultaneously, in Step S10, the signal processor 50 is activated toprocess the detection signal from the sensor electrode 25 and send theprocessed detection signal to the control unit 60. As described above,in the signal processor 50, the amplifier 51 amplifies the detectionsignal from the sensor electrode 25 up to a required level, and sendsthe amplified detection signal to the band-pass filter 52 to passtherethrough only frequency components corresponding to those of thedetection signal so as to eliminate noise components. Then, therectification circuit 53 full-wave-rectifies the filtered detectionsignal from the band-pass filter 52, and the smoothing circuit 54smoothes the full-wave-rectified detection signal and sends the smootheddetection signal to the A/D converter 64.

The CPU 61 activates the A/D converter 64 to convert the input analogsignal to a corresponding digital signal, and reads the detection signaldetected by the sensor electrode 25 in the form of a digital value.

Then, in Step S12, the CPU 61 sends the read detection signal to the ROM63. The ROM stores the read detection signal in a time-series manner.This read detection signal includes the detection signal from all of thetarget patterns including a normal target pattern, a target patternhaving a disconnected region, and a target pattern short-circuited withan adjacent target pattern supplied with the inspection signal.

In Step S14, the CPU 61 determines whether all of the target patternshave been inspected, for example, whether the sensor electrode 25 hasbeen moved to a position beyond the last target pattern (whether theinspection of all of the target patterns has been completed).

If the inspection of a part of the target patterns has not beencompleted, the process will advance to Step S16 to continue scanninglymoving the electrodes and supply the inspection signal to the remainingtarget patterns. Then, the process will return to Step S10 to continuethe read operation.

When the determination in Step S14 is YES or it is determined that allof the target patterns have been inspected, the process advances to StepS20. In Step S20, the CPU 61 instructs the signal supply section 65 tostop supplying the inspection signal, and instructs the signal processor50 and the A/D converter 64 to stop their operations.

Lastly, in Step S22, the target board is taken out of the inspectionzone. Then, the circuit board is positioned at a transfer position, andtransferred to a next station to perform a required remaining operation.

According to the above inspection process, the circuit patterninspection can be performed without any contact between each of thesensor and supply electrodes 25, 35 and each of the target patterns.This allows the circuit board having low-strength target patters to beinspected without occurrence of scratches in the target patters.

Thus, while a glass circuit board for a liquid-crystal display panel tobe used in small portable phones has difficulties in ensuring asufficient strength in wiring patterns, even such wiring patterns can bereliably inspected without damage thereof.

Further, in the inspection process using the inspection apparatusaccording to the first embodiment, the sensor electrode 25 and thesupply electrode 35 are moved across the target patterns to allow thesupply electrode 35 to supply an AC sine-wave signal or continuoussignal to the target patterns and allow the sensor electrode 25 todetect a signal potential from the target patterns. Thus, the signalpotential, or a detection signal obtained from the sensor electrode 25,normally has an approximately constant continuous value.

Thus, if the plurality of target patterns formed on the target boardinclude a defective target pattern having an open region (disconnectedtarget pattern) or a short region short-circuited with an adjacenttarget pattern (short-circuited target pattern), a certain differencewill occur between an approximately constant continuous value detectedat successive positions of normal target patterns without open andshort, and a defective value detected at a position of a defectivetarget pattern with open or short.

As above, a difference or change in value of the detection signal due tothe defect, such as open or short, appears in the detection signalhaving the approximately constant continuous value. For example, thedetection result can be graphed as shown in FIGS. 3 and 4 to facilitatedetermining the presence of defect in the target board and specifying aposition of the defective target pattern with open or short. This willbe described in more detail later.

When the inspection process using the inspection apparatus is performedby continuously replacing a target board with next one, theapproximately constant continuous value of the detection signal variesin absolute value every time the target board is replaced, due tochanges in the gap between the sensor or supply electrode 25, 35 andeach target pattern, and other factor.

Even under this situation, the conductive pattern inspection processusing the inspection apparatus according to the first embodiment makesit possible to determine the presence of defect in the target board andspecify a position of the defective target pattern with open or short(hereinafter referred to as “defective-pattern position”), in accordancewith a change in value appearing in the detection signal having theapproximately constant continuous value due to the defect, such as openor short, or a relative change in detection-signal value.

As a threshold value for determining the presence of defect andspecifying the defective-pattern position, an absolute value of a ratiobetween the continuous value and the defective value or a change rate ofthe defective value in the detection signal may be used. That is,without having to use the approximately constant continuous value as anabsolute value, the inspection process using the inspection apparatuscan be performed to reliable determine the presence of defect in thetarget patterns and specify the defective-pattern position even if atarget board is continuously replaced with next one.

In the conductive pattern inspection process using the inspectionapparatus according to the first embodiment, an additional step ofdetermining whether the detection signal read in Step S12 falls within athreshold range defined by the above absolute value may be providedbetween Steps S12 and S14. In this step, if the detection result is inthe threshold range, the process will advance to Step S14. When thedetection result is not in the threshold range, the target patternsupplied with the inspection signal is considered as the defectivetarget pattern with open or short, and information about the positionand state of the defective target pattern is stored.

An example of a detection signal detected by the sensor electrode 25according to the above inspection process is shown in FIGS. 3 and 4.Specifically, FIG. 3 shows a detection signal obtained when three targetpatterns have a disconnected (open) region, and FIG. 4 shows a detectionsignal obtained when one target pattern has a short-circuited (short)region.

When the target patterns are in the normal state, the inspection signal(AC signal) from the signal supply section 65 to the supply electrode 35is sequentially supplied to each of the target patterns capacitivelycoupled with the supply electrode 35. Then, the inspection signalreaching below the sensor electrode 25 through each of the targetpatterns capacitively coupled with the sensor electrode 25 is detectedby the sensor electrode 25 through the capacitive coupling relative tothe target patterns and the detection signal is output to the controlsection 60.

In this way, the supply electrode 35 and the sensor electrode 25 aremoved across the target patterns to supply and detect the inspectionsignal (AC signal). Thus, the detection signal has an approximatelycontinuous constant value.

When at least one of the target patterns has a disconnected region, atleast a part of the inspection signal (AC signal) from the signal supplysection 65 to the supply electrode 35 does not reach the second ends ofthe target patterns on the side of the sensor electrode 25 due to thedisconnected region of the target pattern, and thereby the detectionsignal has a reduced value. Thus, as shown in FIG. 3, the detectionsignal has a smaller value at a position of the disconnected targetpattern as compared to the constant continuous value detected at thepositions of the normal target patterns

When one of the target patterns has a region short-circuited with theadjacent target pattern, the inspection signal (AC signal) supplied fromthe supply electrode 35 to the short-circuited target pattern also flowsto the adjacent target pattern through the short region, and thereby thedetection signal of the sensor electrode 25 has an increased value,because the detection signal from the adjacent target pattern issuperimposed on the detection signal from the short-circuited targetpattern. Thus, as shown in FIG. 4, the detection signal has a largervalue at a position of the short-circuited target pattern as compared tothe constant continuous value detected at the positions of the normaltarget patterns.

As above, both disconnection and short in the target patterns can bedetected only by the single sensor electrode 25. This can be achievedbecause the sensor electrode 25 is designed to have a width greater thanthat of the supply electrode 35 by at least one pitch of the targetpatterns.

However, it is not essential for the sensor electrode 25 to have a widthgreater than that of the supply electrode 35 by at least one pitch ofthe target patterns. Specifically, the inspection apparatus may bedesigned such that a disconnected target pattern and a target patternshort-circuited with an adjacent target pattern supplied with theinspection signal are individually inspected, for example, as in asecond embodiment described in detail later.

In this case, a given threshold range may be set based on the absolutevalue of the approximately constant continuous value of the detectionsignal, so that the determination on the disconnected target pattern ismade when the detection signal has a value less than a lower thresholdvalue, and the determination on the short-circuited pattern is made whenthe detection signal has a value greater than an upper threshold value.For example, in FIG. 4, given that a threshold range is set at 0.02 Vppbased on the approximately constant continuous value or 0.66 Vpp, eachof the target patterns located at respective sensor-movement distancesof about 22, 42 and 78 mm is determined as the disconnected targetpattern, because they have a value less than a lower threshold value of0.58.

When an absolute value of a ratio between the continuous value and thedefective value or a change rate of the defective value in the detectionsignal is used as a threshold value for determining the presence ofdefect in the target patterns and specifying the defective-patternposition, the determination on the disconnected target pattern may bemade when the continuous value goes down at 3% or more, and thedetermination on the short-circuited pattern may be made when thecontinuous value goes up at 3% or more.

As above, in this embodiment, not only an absolute value but also arelative change of the value of the defective target pattern to thevalue of the normal target patterns in the detection signal can be usedas a threshold value for determining the presence of defect in thetarget patterns. Thus, even if the inspection process using theinspection apparatus is performed by continuously replacing a targetboard with next one, an optimal threshold value can be set depending ona detection result. That is, even if the continuous value of thedetection signal has variation in each inspection or becomes lower,adverse affects thereof can be fully prevented to obtain an accurateinspection result.

While the detection signal obtained through this inspection process hasa minute value due to the sensor section and the inspection signalsupply section each designed in the non-contact type, the inspectionapparatus according to the first embodiment makes it possible toreliably distinguish a change in the minute value so as to inspect thestate of each target patterns readily and reliably.

Thus, as compared to a conventional method using only the absolute valueof the detection signal as a threshold value for determining thepresence of defect in the target patterns, the presence of defect in thetarget patterns can be determined with significantly enhanced accuracyand simplicity. In addition, the inspection apparatus designed in thenon-contact type can eliminate the need for accurate positioning toinspect a circuit board with a high degree of accuracy even if it hastarget patterns arranged in an extremely fine pitch.

Second Embodiment

The inspection apparatus according the first embodiment is designed suchthat at least a portion of the sensor electrode 25 is essentiallylocated opposed to the second end of a target pattern currently suppliedwith the inspection signal from the supply electrode 35. The presentinvention is not limited to the first embodiment. For example, aplurality of sensor electrodes 25 may be provided, wherein one of thesensor electrodes 25 is located opposed to the second end of a firsttarget pattern currently supplied with the inspection signal from thesupply electrode 35, and at least one of the remaining sensor electrodes25 is located opposed to the second end of a second target patternadjacent to the first target pattern.

A circuit pattern inspection apparatus according to a second embodimentof the present invention is designed based on this technical concept.With reference to FIG. 5, the inspection apparatus according to thesecond embodiment will be described below.

In FIG. 5, the same element or component as that of the inspectionapparatus according to the first embodiment illustrated in FIG. 1 isdefined by the same reference numeral, and its detailed description willbe omitted.

Referring to FIG. 5, a first sensor electrode 22 and a second electrode24 are provided on at least a top surface of a sensor section 20. Thefirst and second sensor electrodes 22, 24 are spaced apart from oneanother by one pitch of a plurality of target patterns 15. Morespecifically, the first second sensor electrodes 22, 24 are arranged onthe sensor section 20 in such a manner that, when the sensor section 20and a supply electrode 35 is synchronizingly moved, the first secondsensor electrode 22 is located opposed to the second end of the targetpattern currently supplied with an inspection signal from a supplyelectrode 35 (such a target pattern will hereinafter be referred to as“signal-receiving target pattern”), and the second sensor electrode 24is located opposed to the second end of the target pattern adjacent tothe signal-receiving target pattern (such a target pattern willhereinafter be referred to as “adjacent target pattern”).

Preferably, each of the first second sensor electrodes 22, 24 has awidth equal to or less than each width of the target patterns. Thissetting is intended to assign to the first sensor electrode 22 a role ofinspecting the presence of disconnection in the signal-receiving targetpattern and to the second electrode 24 a role of inspecting the presenceof short-circuit between the signal-receiving target pattern and theadjacent target pattern, so as to achieve a highly accurate inspection.

Specifically, even if the signal-receiving target pattern isshort-circuited with the adjacent target pattern, the first sensorelectrode 22 having a width equal to or less than each width of thetarget patterns can suppress an affect of a detection signal from theadjacent target pattern, which is caused by the inspection signalflowing in the adjacent target pattern from the signal-receiving targetpattern through a short-circuited region. Further, when the targetpatterns have neither disconnection nor short, and even if thesignal-receiving target pattern has no disconnection but a short-circuitwith the adjacent target pattern, the second sensor electrode 24 havinga width equal to or less than each width of the target patterns cansuppress an affect of a detection signal from the signal-receivingtarget pattern.

Thus, the inspection of disconnection and short-circuit using the firstand second sensor electrodes 22, 24 can be performed with asignificantly high degree of accuracy, regardless of whether thesignal-receiving target pattern has a disconnection and whether thesignal-receiving target pattern has a short-circuit with the adjacenttarget pattern.

However, as seen in the sensor electrode 25 in the first embodiment, itis not essential for the first and second sensor electrodes 22, 24 tohave a width equal to or less than each width of the target patterns.

While the inspection apparatus according to the second embodiment hasonly the second sensor electrode 24 as a sensor electrode to be locatedopposed to the adjacent target pattern, a third sensor electrode may beadditionally provided to obtain a detection signal from another adjacenttarget pattern on the opposite side of the above adjacent target patternrelative to the signal-receiving target pattern. The addition of thethird sensor electrode makes it possible to simultaneously detectwhether the signal-receiving target pattern is short-circuited witheither one or both of the two adjacent target patterns.

Further, it is to be understood that the sensor section 20 may beprovided with only the first electrode 22 or only the second sensorelectrode 24, or may be provided with three or more of the sensorelectrodes to be located opposed, respectively, to three or moreadjacent target patterns.

Third Embodiment

While the aforementioned inspection apparatuses according to the firstand second embodiments are designed to move the sensor electrode 25 andthe supply electrode 35 across the ends of the target patterns so as todetect a defective target pattern, the present invention is not limitedto such embodiments. For example, either one of the sensor electrode 25and the supply electrode 35 may be designed to be controllably movedalong each of the target patterns, wherein, when a defective targetpattern is detected and discriminated by the aforementioned process, thesupply and sensor electrodes are positioned at the first and second endsof the defective target pattern, and one of the electrodes is movedalong the defective target pattern to read a value of a detection signalfrom the sensor electrode 25 so as to detect a position where the valueof the detection signal is changed, and specify the position as adefective-region position in the defective target pattern.

A circuit pattern inspection apparatus according to a third embodimentof the present invention is designed based on this technical concept.The inspection apparatus according to the third embodiment will bedescribed below with reference to FIGS. 6 to 10, wherein: FIG. 6 is ablock diagram showing the inspection apparatus; FIG. 7 is an explanatorydiagram of a process of moving electrodes, in the inspection apparatus;FIG. 8 is a flowchart of a process of specifying a defective-patternposition, in the inspection apparatus; FIG. 9 is a waveform chartshowing one example of a detection signal obtained from a defectivetarget pattern through a sensor electrode 25 in the inspectionapparatus; and FIG. 10 is a waveform chart showing one example of adetection signal obtained from a defective target pattern through thesensor electrode 25.

In FIG. 6, the same element or component as that of the inspectionapparatus according to the first embodiment illustrated in FIG. 1 isdefined by the same reference numeral, and its detailed description willbe omitted.

Referring to FIG. 6, a camera 26 is attached to a sensor section 20.This camera 26 is disposed to take or pick up an image of targetpatterns 15, and connected, for example, to a display section 66 of acontrol section to display the image so as to observe the state of adefective target pattern. Further, a probe-contacting device 32 isprovided in an inspection signal supply section 30, and an inspectionsignal supply probe for supplying an inspection signal to a defectivetarget pattern is attached to the probe-contacting device 32. Theprobe-contacting device 32 and the inspection signal supply probe areused for reliably specifying the defective-region position.

In the third embodiment, a scalar robot 80 is designed to controllablymove at least one of the supply and sensor electrodes along not onlydirections indicated by the arrows in FIG. 6 but also a longitudinaldirection of the target patterns 15.

As with the inspection apparatus according to the first embodiment, itis firstly inspected whether a defect exists in the target patterns,through the process described in the flowchart of FIG. 2. As the resultof the inspection, if a defective target pattern, such as a disconnectedtarget pattern, is detected, a position of the defective target patternor a defective-pattern position will be stored, for example, in a ROM63.

After detecting the defective target pattern and specifying thedefective-pattern position in the above way, a process of specifying adefective-region position is performed. In the process of specifying adefective-region position using the inspection apparatus according tothe third embodiment, a supply electrode 35 and the sensor electrode 25are synchronizingly moved in a direction indicated by the arrows (1) inFIG. 7 to the defective-pattern position.

Then, the sensor electrode 25 is moved from the second end toward thefirst end of the defective target pattern, as indicated by the arrow (2)in FIG. 7, to continuously obtain a detection signal so as to detect aposition where the read signal is sharply changed (a position where thedetection signal is changed to a zero or lower level) and specify thedetected position as a defective-region position.

With reference to the flowchart in FIG. 8, the process of specifying adefective-region position will be described in more detail below. Inadvance of the process using the inspection apparatus according to thethird embodiment, after Step S14 in the aforementioned first embodiment,the detection signal stored in the RAM 63 is checked to determinewhether a defective target pattern has been detected. If it isdetermined that no defective target patter is detected, the process willadvance to Step S20.

When it is determined that a defective target position has been detectedas the result of the inspection, each of the supply and sensorelectrodes is moved to the initial position as in Step S3 in FIG. 2, andthe process is shifted to the routine as shown in FIG. 8. Aftercompletion of the routine in FIG. 8, the process may be shifted to StepS20.

As shown in FIG. 8, in the inspection process using the inspectionapparatus according to the third embodiment, a defective-patternposition is firstly specified in Step S31, based on the detection signalobtained through Steps S1 to S16 in FIG. 2. For example, the waveform ofa detection signal obtained when a part of the target patterns have adisconnected region is shown in FIG. 9. The example illustrated in FIG.9 shows a signal waveform before the signal processing in the analogsignal processor 50. The encircled portion of the signal waveformcorresponds to a position of the target pattern having an open region(in this example, two of the target patterns has a disconnected region).

Then, in Step S33, the robot controller 70 is activated to control thescalar robot 80 in such a manner that the sensor electrode 25 and thesupply electrode 35 are synchronizingly moved to the defective-patternposition. In order to detect a defective region with high sensitivity,each of the sensor and supply electrodes 25, 35 is moved to a positionwhere a width-directional center thereof approximately corresponds to awidth-directional center of the defective target pattern (see the arrows(1) in FIG. 7).

Subsequently, the process advances to Step S35. In Step S35, a signalsupply section 65 is activated to apply an inspection signal to thesupply electrode 35 so as to supply the inspection signal to thedefective target pattern. Then, under the control of the robotcontroller 70, the sensor 25 is moved along the defective target patterntoward the supply electrode 35 (see the arrow (2) in FIG. 7).

Concurrently, in Step S40, a detection signal from the sensor electrode25 is read. Then, in Step S42, it is determined whether a significantchange in value of the detection signal from the sensor electrode 25 hasbeen detected. If it is determined that no significant change has notbeen detected, the process will return to Step S37 to continue themovement of the sensor electrode 25.

When the determination in Step S42 is YES or it is determined that asignificant change in value of the detection signal from the sensorelectrode 25 has been detected, the process advances to Step S44. InStep S44, a first position where the significant change initiallyappeared in the detection signal and a second position where thesignificant change disappeared are determined, and an intermediateposition between the first and second positions are specified as adefective-region position.

One example of the waveform of such a detection signal from the sensorelectrode 25 is shown in FIG. 10. As shown in FIG. 10, before the sensorelectrode 25 is moved beyond a disconnected region, the inspectionsignal supplied from the supply electrode 35 does not reach the sensorelectrode 25, and thereby the detection signal has a low value. Then,when the sensor electrode 25 is moved beyond the disconnected region,the inspection signal reaches the sensor electrode 25 to increase thevalue of the detection signal. Given that an intermediate positionbetween a first position where the significant change initially appearedin the detection signal from the sensor electrode 25 and a secondposition where the significant change disappeared is specified as adefective-region position, as in this embodiment, approximately anintermediate position of the inclined waveform in FIG. 10 is specifiedas a defective-region position.

The above inspection apparatus is designed to move the sensor electrode25 toward the supply electrode 35. Alternatively, instead of the sensorelectrode 25, the supply electrode 35 may be moved toward the sensorelectrode 25.

As above, the inspection apparatus according to the third embodimentmakes it possible to inspect the presence of defect in the targetpatterns with a high degree of accuracy as with the first embodiment.Further, the inspection apparatus according to the third embodiment isdesigned to move the sensor electrode in X-Y two directions. Thus, inaddition to the inspection of the presence of a defective targetpattern, a defective-region position can be specified. This allows thedefective region to be promptly repaired according to need.

In the repair of the defective region, it is desirable to allow thestate of the defective region to be visually observed so as to determinewhether the defective region is repairable. For example, if it isobserved that the defective region is simply caused by a dust attachedthereto, it will be determined that the defective region is repairable.In contrast, if it is observed that the defective region has a fatalflaw, it can be determined that no repair is performed. Theaforementioned camera 26 attached to the sensor section 20 is used inthe observation of the state of the defective region. The camera 26attached to the sensor section 20 starts picking up an image in StepS35. Then, the camera continuously picks up an image during Steps S40 toS44 or until the defective-region position is specified in Step S44. Themage of the defective region picked up in this way may be displayed onthe display section 66 during the image pickup and even after thedefective-region position is specified, to observe the state of thedefective region in the defective target pattern.

The defective region includes various states, such as a complete open orshort state, a partial open state, and a partial short state due toattached foreign substance, such as dust. In the inspection using thesensor electrode 25 and the supply electrode 35 each designed in anon-contact type, if a defective target pattern is in the partial openor short state, it can be difficult to obtain the waveform of thedetection signal as in FIG. 10. In this case, the aforementionedprobe-contacting device 32 is activated to bring the inspection signalsupply probe into contact with the first end, and then the sensorelectrode 25 is moved along the defective target pattern. This makes itpossible to reliably specify a defective-region position.

Alternatively, in place of the sensor electrode 25 located opposed tothe second end of the defective target pattern, a contact-type sensorprobe may be used. In this case, the sensor probe is brought in contactwith the second end of the defective target pattern, and the non-contacttype supply electrode 35 is moved toward the sensor probe located on thefirst end of the defective target pattern.

Fourth Embodiment

The inspection apparatus according to the third embodiment is designedto move the sensor electrode 25 and the supply electrode 352-dimensionally or in the X-Y directions. This control is performedbecause the target board is a circuit board for a liquid-crystal panel,and a glass circuit board having a high degree of flatness. In aninspection of a circuit board formed with a conductive pattern having alarge thickness, or a large circuit board inevitably havingirregularities in a surface thereof, the inspection apparatus may bedesigned to move the sensor electrode 25 and the supply electrode 35 notonly 2-dimensionally but also in a vertical (Z) direction, so as toobtain an adequate inspection result regardless of the presence ofirregularities in the surface of the target board.

Based on this technical concept, a circuit pattern inspection apparatusaccording to a fourth embodiment of the present invention is designed tomove a sensor section and an inspection signal supply section not only2-dimensionally but also in a vertical (Z) direction. The inspectionapparatus according to the fourth embodiment will be described belowwith reference to FIG. 11. In FIG. 11, the same element or component asthat of the inspection apparatus according to the first embodimentillustrated in FIG. 1 is defined by the same reference numeral, and itsdetailed description will be omitted.

Referring to FIG. 11, the inspection apparatuses includes first andsecond laser displacement measurement devices 28, 38 attached,respectively, to a sensor section 20 and an inspection signal supplysection 30, and a gap measurement section 90 for measuring a gap betweeneach of the sensor section 20 and the inspection signal supply section30 and a surface of a target board 10 or each of a plurality of targetpatterns formed thereon, in accordance with a detection result from eachof the first and second displacement measurement devices 28, 38.

Further, the scalar robot 80 is designed to move each of the sensorsection 20 and the inspection signal supply section 30 2-dimensionallyand in a direction perpendicular to the drawing sheet (a verticaldirection).

In the above inspection apparatus according to fourth embodiment, inconjunction with the movement of a sensor electrode 25 and a supplyelectrode 35, the gap measurement section 90 activates the first andsecond laser displacement measurement devices 28, 38 to measure a gapbetween each of the electrodes and the surface of the target board, andoutputs the measurement result to a control section 60. The controlsection 60 is operable to average the measurement result obtained by thegap measurement section 90 in a period where each of the electrodes ismoved by a given distance, and control the gap between each of theelectrodes and each of the target patterns in such a manner that theaveraged gap is maintained at a constant value.

For example, the gap between each of the electrodes and the surface ofthe target board is controlled in accordance with an averaged gap of themeasurement result obtained in a period where each of the electrodes ismoved by a distance between the three adjacent target patterns Theaveraging of the measured gaps is performed for moving the electrodes ata moderate speed in the Z-direction without an excessively rapidcontrol, and reducing an adverse affect, such as noises or measurementerror.

The 3-dimensional or X, Y, Z-control is effective, particularly, in aninspection of large circuit boards. For example, while a circuit boardfor a large flat display panel has difficulties in avoiding a curvatureof a surface thereof, the 3-dimensional control can effectively preventthe contact between each of the electrodes and target patterns on thesurface of the circuit board during inspection.

Further, if the target patterns have a large thickness, the distance formeasuring gaps to be averages may be reduced to provide enhanceddetection sensitivity.

INDUSTRIAL APPLICABILITY

As mentioned above, according to the present invention, the presence ofdefect in target patterns can be reliably detected.

Further, the state of a defective target pattern can be readilyrecognized, and the position of a defective region can be specified.

Furthermore, even if a target board has a surface with irregularities orcurvature, it can be reliably inspected without damages of targetpatterns thereon.

1. A circuit pattern inspection apparatus for inspecting a plurality oftarget patterns having first and second opposite ends included in aninspection region thereof and arrange in lines, which is adapted tosupply an AC inspection signal from the first end side of saidinspection region of said target patterns, and detect a signal from thesecond end side of said inspection region, said circuit patterninspection apparatus comprising: supply means including a supplyelectrode for supplying said inspection signal from the first end sideof said inspection region of said target patterns; detection meansincluding a sensor electrode for detecting a signal from each of saidtarget patterns; and moving means for moving said supply and sensorelectrodes, respectively, across said first and second ends included insaid inspection region and arrange in lines, with a given gap relativeto each of said target patterns.
 2. The circuit pattern inspectionapparatus as defined in claim 1, wherein each of said target patterns isa conductive pattern formed on a circuit board, said conductive patternhaving a bar-like shape with a given width.
 3. The circuit patterninspection apparatus as defined in claim 1 or 2, wherein said sensorelectrode has a width equal to or greater than a width of two lines ofsaid target patterns.
 4. The circuit pattern inspection apparatus asdefined in claim 1 or 2, wherein said sensor electrode includes: a firstsensor electrode adapted to be disposed at a position opposed to thesecond end of one of the adjacent target patterns which has the firstend supplied with the inspection signal from said supply electrode; anda second sensor electrode adapted to be disposed at a position opposedto the second end of a remaining one of said adjacent target patterns.5. The circuit pattern inspection apparatus as defined in claim 4,wherein said first sensor electrode has a width equal to or less thaneach width of said target patterns.
 6. The circuit pattern inspectionapparatus as defined in claim 4, wherein said second sensor electrodehas a width equal to or less than each width of said target patterns. 7.The circuit pattern inspection apparatus as defined in claim 1 or 2,wherein said moving means is adapted to move said supply and sensorelectrodes, respectively, across said first and second ends included insaid inspection region and arrange in lines, under the condition thateach surface of said supply and sensor electrodes is capacitivelycoupled with each of said target patterns.
 8. The circuit patterninspection apparatus as defined in claim 1 or 2, which further includesdetermination means operable, when a detection result of said detectionmeans based on a detection signal from one of said target patters is ina given acceptable range, to determine that said target pattern isnormal, and, when a detection result of said detection means based on adetection signal from one of said target patters is out of said givenacceptable range, to determine that said target pattern is defective. 9.The circuit pattern inspection apparatus as defined in claim 8, whichincludes: second moving means for moving said supply and sensorelectrodes to respective positions opposed to the first and second endsof said defective target pattern determined by said determination means,and moving either one of said supply and sensor electrodes along saiddefective target pattern toward the other electrode; and positiondetection means for detecting a position where a detection signal fromsaid defective target pattern has a change, in accordance with adetection result of said detection means.
 10. The circuit patterninspection apparatus as defined in claim 9, which includes contactingmeans for bringing either one of said supply and sensor electrodes intocontact with said defective target pattern.
 11. The circuit patterninspection apparatus as defined in claim 9, wherein at least one of saidsupply and sensor electrodes which is to be moved by said second movingmeans includes an image pickup means.
 12. The circuit pattern inspectionapparatus as defined in claim 9, which includes a gap control means forpositioning at least one of said supply and sensor electrodes which isto be moved by said second movement means, in such a manner as to allowa gap between said at least one electrode and said defective targetpattern to be maintained at an approximately constant value.
 13. Thecircuit pattern inspection apparatus as defined in claim 1 or 2, whichincludes a gap control means for positioning at least one of said supplyand sensor electrodes to be moved by said movement means, in such amanner as to allow a gap between said at least one electrode and each ofsaid target patterns to be maintained at a constant value.
 14. Thecircuit pattern inspection apparatus as defined in claim 12, whereinsaid gap control means includes a displacement measurement devicedisposed at a position adjacent to said sensor or supply electrode andadapted to be moved together with said sensor or supply electrode, saidgap control means being operable to position said sensor or supplyelectrode in a direction orthogonal to said inspection region inaccordance with a detection result of said displacement measurementdevice, in such a manner as to allow a gap between said sensor or supplyelectrode and said inspection region to be maintained at anapproximately constant value
 15. The circuit pattern inspectionapparatus as defined in claim 14, wherein said gap control means isoperable to position said sensor or supply electrode in a directionorthogonal to said inspection region, on the basis of a gap between saidsensor or supply electrode and said inspection region which is definedby an average displacement of a detection result of said displacementmeasurement device obtained from a plurality of pitches of said targetpatterns.
 16. A circuit pattern inspection method for use in a circuitpattern inspection apparatus which comprises supply means including asupply electrode for supplying an inspection signal to each of aplurality of target patterns having first and second opposite endsincluded in an inspection region thereof and arrange in lines, from thefirst end side of said inspection region, and detection means includinga sensor electrode for detecting a signal from each of said targetpatterns, said circuit pattern inspection method comprising: moving saidsupply and sensor electrodes relative to said target patterns,respectively, across said first and second ends included in saidinspection region and arrange in lines, under the condition that eachsurface of said supply and sensor electrodes is spaced apart from eachsurface of said target patterns; supplying an AC inspection signal fromthe first end side of said inspection region of said target patterns;and detecting a signal from each of said target patterns to inspect saidtarget patterns.
 17. The circuit pattern inspection method as defined inclaim 16, wherein each of said target patterns is a conductive patternformed on a circuit board, said conductive pattern having a bar-likeshape with a given width.
 18. The circuit pattern inspection method asdefined in claim 17, which includes: allowing said sensor electrode tohave a width equal to or greater than a width of two lines of saidtarget patterns; and detecting a signal from one of the adjacent targetpatterns a remaining one of which is supplied with the inspectionsignal, so as to allow the presence of short circuit between saidadjacent target patterns to be determined.
 19. The circuit patterninspection method as defined in claim 16 or 17, which includes:detecting a signal from one of the adjacent target patterns which issupplied with the inspection signal, through a first sensor electrodeincluded in said sensor electrode so as to allow the presence ofdisconnection in said target pattern to be determined; and detecting asignal from a remaining one of said adjacent target patterns through asecond sensor electrode included in said sensor electrode so as to allowthe presence of short circuit between said adjacent target patterns tobe determined.
 20. The circuit pattern inspection method as defined ineither one of claims 16 to 18, which includes determining a generalposition of a disconnected region in the target pattern in accordancewith a position of said sensor electrode where said detection means hasno detection signal.
 21. The circuit pattern inspection method asdefined in either one of claims 16 to 18, which includes evaluatingwhether a detection result of said detection means based on a detectionsignal from one of said target patters is in a given acceptable range,wherein when said detection result is in a given acceptable range,determining that said target pattern is normal, and, when said detectionresult is out of said given acceptable range, determining that saidtarget pattern is defective.
 22. The circuit pattern inspection methodas defined in claim 21, which includes: specifying a position of saiddefective target pattern determined by said determination means, andstoring information about said position; moving said supply and sensorelectrodes to respective positions opposed to the first and second endsof said defective target pattern in accordance with said storedinformation; moving either one of said supply and sensor electrodesalong said defective target pattern toward the other electrode; anddetecting a position where a detection signal from said defective targetpattern has a change, in accordance with a detection result of saiddetection means, and defining said position as a defective position. 23.The circuit pattern inspection method as defined in claim 22, whichincludes bringing either one of said supply and sensor electrodes intocontact with said defective target pattern.
 24. The circuit patterninspection method as defined in claim 22, which includes: providingimage pickup means in either one of said supply and sensor electrodes;and moving said image pickup means together with said at least oneelectrode along said defective target pattern toward the otherelectrode.
 25. The circuit pattern inspection method as defined ineither one of claims 16 to 18, which includes; providing a displacementmeasurement device disposed at a position adjacent to said sensor orsupply electrode and adapted to be moved together with said sensor orsupply electrode; and positioning said sensor or supply electrode in adirection orthogonal to said inspection region in accordance with adetection result of said displacement measurement device, in such amanner as to allow a gap between said sensor or supply electrode andsaid inspection region to be maintained at an approximately constantvalue, so as to provide a stable detection result of said detectionmeans.
 26. The circuit pattern inspection method as defined in claim 25,which includes positioning said sensor or supply electrode on the basisof a gap between said sensor or supply electrode and said inspectionregion which is defined by an average displacement of a detection resultof said displacement measurement device obtained from a plurality ofpitches of said target patterns.